1// SPDX-License-Identifier: GPL-2.0
2/*
3 * arch/alpha/boot/bootp.c
4 *
5 * Copyright (C) 1997 Jay Estabrook
6 *
7 * This file is used for creating a bootp file for the Linux/AXP kernel
8 *
9 * based significantly on the arch/alpha/boot/main.c of Linus Torvalds
10 */
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/string.h>
14#include <generated/utsrelease.h>
15#include <linux/mm.h>
16
17#include <asm/console.h>
18#include <asm/hwrpb.h>
19#include <asm/io.h>
20
21#include <linux/stdarg.h>
22
23#include "ksize.h"
24
25extern unsigned long switch_to_osf_pal(unsigned long nr,
26 struct pcb_struct *pcb_va, struct pcb_struct *pcb_pa,
27 unsigned long *vptb);
28
29extern void move_stack(unsigned long new_stack);
30
31struct hwrpb_struct *hwrpb = INIT_HWRPB;
32static struct pcb_struct pcb_va[1];
33
34/*
35 * Find a physical address of a virtual object..
36 *
37 * This is easy using the virtual page table address.
38 */
39
40static inline void *
41find_pa(unsigned long *vptb, void *ptr)
42{
43 unsigned long address = (unsigned long) ptr;
44 unsigned long result;
45
46 result = vptb[address >> 13];
47 result >>= 32;
48 result <<= 13;
49 result |= address & 0x1fff;
50 return (void *) result;
51}
52
53/*
54 * This function moves into OSF/1 pal-code, and has a temporary
55 * PCB for that. The kernel proper should replace this PCB with
56 * the real one as soon as possible.
57 *
58 * The page table muckery in here depends on the fact that the boot
59 * code has the L1 page table identity-map itself in the second PTE
60 * in the L1 page table. Thus the L1-page is virtually addressable
61 * itself (through three levels) at virtual address 0x200802000.
62 */
63
64#define VPTB ((unsigned long *) 0x200000000)
65#define L1 ((unsigned long *) 0x200802000)
66
67void
68pal_init(void)
69{
70 unsigned long i, rev;
71 struct percpu_struct * percpu;
72 struct pcb_struct * pcb_pa;
73
74 /* Create the dummy PCB. */
75 pcb_va->ksp = 0;
76 pcb_va->usp = 0;
77 pcb_va->ptbr = L1[1] >> 32;
78 pcb_va->asn = 0;
79 pcb_va->pcc = 0;
80 pcb_va->unique = 0;
81 pcb_va->flags = 1;
82 pcb_va->res1 = 0;
83 pcb_va->res2 = 0;
84 pcb_pa = find_pa(VPTB, pcb_va);
85
86 /*
87 * a0 = 2 (OSF)
88 * a1 = return address, but we give the asm the vaddr of the PCB
89 * a2 = physical addr of PCB
90 * a3 = new virtual page table pointer
91 * a4 = KSP (but the asm sets it)
92 */
93 srm_printk("Switching to OSF PAL-code .. ");
94
95 i = switch_to_osf_pal(2, pcb_va, pcb_pa, VPTB);
96 if (i) {
97 srm_printk("failed, code %ld\n", i);
98 __halt();
99 }
100
101 percpu = (struct percpu_struct *)
102 (INIT_HWRPB->processor_offset + (unsigned long) INIT_HWRPB);
103 rev = percpu->pal_revision = percpu->palcode_avail[2];
104
105 srm_printk("Ok (rev %lx)\n", rev);
106
107 tbia(); /* do it directly in case we are SMP */
108}
109
110static inline void
111load(unsigned long dst, unsigned long src, unsigned long count)
112{
113 memcpy(to: (void *)dst, from: (void *)src, len: count);
114}
115
116/*
117 * Start the kernel.
118 */
119static inline void
120runkernel(void)
121{
122 __asm__ __volatile__(
123 "bis %0,%0,$27\n\t"
124 "jmp ($27)"
125 : /* no outputs: it doesn't even return */
126 : "r" (START_ADDR));
127}
128
129extern char _end;
130#define KERNEL_ORIGIN \
131 ((((unsigned long)&_end) + 511) & ~511)
132
133void
134start_kernel(void)
135{
136 /*
137 * Note that this crufty stuff with static and envval
138 * and envbuf is because:
139 *
140 * 1. Frequently, the stack is short, and we don't want to overrun;
141 * 2. Frequently the stack is where we are going to copy the kernel to;
142 * 3. A certain SRM console required the GET_ENV output to stack.
143 * ??? A comment in the aboot sources indicates that the GET_ENV
144 * destination must be quadword aligned. Might this explain the
145 * behaviour, rather than requiring output to the stack, which
146 * seems rather far-fetched.
147 */
148 static long nbytes;
149 static char envval[256] __attribute__((aligned(8)));
150 static unsigned long initrd_start;
151
152 srm_printk("Linux/AXP bootp loader for Linux " UTS_RELEASE "\n");
153 if (INIT_HWRPB->pagesize != 8192) {
154 srm_printk("Expected 8kB pages, got %ldkB\n",
155 INIT_HWRPB->pagesize >> 10);
156 return;
157 }
158 if (INIT_HWRPB->vptb != (unsigned long) VPTB) {
159 srm_printk("Expected vptb at %p, got %p\n",
160 VPTB, (void *)INIT_HWRPB->vptb);
161 return;
162 }
163 pal_init();
164
165 /* The initrd must be page-aligned. See below for the
166 cause of the magic number 5. */
167 initrd_start = ((START_ADDR + 5*KERNEL_SIZE + PAGE_SIZE) |
168 (PAGE_SIZE-1)) + 1;
169#ifdef INITRD_IMAGE_SIZE
170 srm_printk("Initrd positioned at %#lx\n", initrd_start);
171#endif
172
173 /*
174 * Move the stack to a safe place to ensure it won't be
175 * overwritten by kernel image.
176 */
177 move_stack(new_stack: initrd_start - PAGE_SIZE);
178
179 nbytes = callback_getenv(ENV_BOOTED_OSFLAGS, envval, sizeof(envval));
180 if (nbytes < 0 || nbytes >= sizeof(envval)) {
181 nbytes = 0;
182 }
183 envval[nbytes] = '\0';
184 srm_printk("Loading the kernel...'%s'\n", envval);
185
186 /* NOTE: *no* callbacks or printouts from here on out!!! */
187
188 /* This is a hack, as some consoles seem to get virtual 20000000 (ie
189 * where the SRM console puts the kernel bootp image) memory
190 * overlapping physical memory where the kernel wants to be put,
191 * which causes real problems when attempting to copy the former to
192 * the latter... :-(
193 *
194 * So, we first move the kernel virtual-to-physical way above where
195 * we physically want the kernel to end up, then copy it from there
196 * to its final resting place... ;-}
197 *
198 * Sigh... */
199
200#ifdef INITRD_IMAGE_SIZE
201 load(initrd_start, KERNEL_ORIGIN+KERNEL_SIZE, INITRD_IMAGE_SIZE);
202#endif
203 load(START_ADDR+(4*KERNEL_SIZE), KERNEL_ORIGIN, KERNEL_SIZE);
204 load(START_ADDR, START_ADDR+(4*KERNEL_SIZE), KERNEL_SIZE);
205
206 memset((char*)ZERO_PGE, 0, PAGE_SIZE);
207 strcpy((char*)ZERO_PGE, envval);
208#ifdef INITRD_IMAGE_SIZE
209 ((long *)(ZERO_PGE+256))[0] = initrd_start;
210 ((long *)(ZERO_PGE+256))[1] = INITRD_IMAGE_SIZE;
211#endif
212
213 runkernel();
214}
215

source code of linux/arch/alpha/boot/bootp.c